Frequently Asked Questions about Sun NVRAM/hostid
$Date: 1997/06/06 23:20:56 $
$Revision: 1.43 $
This document has been placed in the public domain by the author - Mark

If this information is abused, misinterpreted, or incorrect you can render
your computer unbootable. The information in this document is distributed in
the hope that it will be useful, but without any warranty; without even the
implied warranty of merchantability or fitness for a particular purpose. You
use this document at your own risk. The author disclaims responsibility for
any damages that might result from the use of this document, even if they
result from negligence or errors on the part of the author. Please do not
use the information in this document to steal software or violate licence
agreements with software vendors.

This is the new and hopefully improved Sun NVRAM FAQ. It is an attempt to
answer the following frequently asked questions on comp.sys.sun.hardware and

  1. When I turn on my Sun I get output which looks something like:

     Sun Workstation, Model Sun-XXXXXX Series.
     ROM Rev X.X, XXMB memory installed
     ID PROM invalid.
     Testing 0 Megabytes of Memory ... Completed.
     ERROR: missing or invalid ID prom
     Requesting Internet address for 0:0:0:0:0:0


     Sun Workstation, Model Sun-XXXX Series.
     Type 4 Keyboard
     ROM Rev X.X, XXMB memory installed, Serial #16777215
     Ethernet address ff:ff:ff:ff:ff:ff, Host ID ffffffff

     Invalid format type in NVRAM
     The IDPROM contents are invalid

     How can I fix this? (Probably Replace chip)
  2. The clock on my Sun has stopped working. When I turn off the machine it
     loses track of the time and/or complains about invalid TOD when I turn
     it on. How do I get my clock to keep time when the system is off?
     (Replace chip)
  3. I get warnings about by NVRAM battery being low when I boot my machine
     but otherwise it works nicely. Should I be worried? (Replace chip)
  4. When my Sun boots I get warnings about the IDPROM checksum being
     incorrect and/or Invalid format type in NVRAM. What does this mean and
     how can I fix it?
  5. The hostid and/or ethernet address on my Sun have been corrupted. How
     can I restore it to a sane state?
  6. How do I change the hostid and/or ethernet address of my Sun
  7. My Sun is in full-security mode (can't even boot without password) and
     I don't know the EEPROM password. How do I fix this? (Replace chip)

The information in this document applies to the following Sun architectures:
sun4c, sun4m, sun4d, sun4u, sun3x (but not to sun4, sun3)

All of these questions relate to the NVRAM chip in the Sun workstation. The
contents of the NVRAM chip can become corrupted for a variety of reasons,
most commonly, failure of the embedded battery. The battery embedded in the
NVRAM chip keeps the clock running when the machine is off and also
maintains important system configuration information. This FAQ tells you how
to reprogram your NVRAM chip and where to buy a new one, should you need to
replace your current NVRAM chip. If you have one of the questions marked
(Replace Chip), you'll need to purchase a new NVRAM chip. The cost is about
US$20. For the other questions, as long as your machine retains its hostid
and ethernet address when turned off, and the clock keeps time when the
machine is turned off, reprogramming your NVRAM chip is enough.

One question is marked (Probably Replace Chip). Usually, when the NVRAM gets
corrupted in this way, this is a symptom that the battery embedded in the
NVRAM chip has run out and you need to replace the chip. If the machine is
relatively new, you should try reprogramming the NVRAM chip with a hostid
and ethernet address using the instructions below, then do a reset at the
"ok" prompt to make sure the banner looks as expected. Next turn the machine
off for a couple of minutes and turn it on again. If the machine retains its
hostid and ethernet address, then you probably don't need to replace the
NVRAM chip.

People can be asking two different questions when they are asking how to
change the ethernet address of a workstation. If you merely want to change
the ethernet address of an interface on your system, you can use the
ifconfig command and forget about the procedures in this document. The
ethernet address in NVRAM is the default address for all ethernet
interfaces. If, for some reason, you want to change this default ethernet
address in NVRAM, then the instructions in this document will tell you how
to do this. Sun workstations are a little strange in this regard, they don't
get their MAC addresses from the ethernet hardware itself.

The most up to date version of this document can be obtained from the
following sites:


Plain text versions of this document are available from the following:


This FAQ is also distributed as part of a larger package for spoofing the
hostid on Sun workstations called change-sun-hostid. In particular, parts of
change-sun-hostid can be used to modify the apparent hostid for some or all
processes on a UNIX system without messing with the NVRAM. This package even
provides a way to make a host seem to have multiple hostids (different
processes see different hostids). If you are interested in changing your
hostid to deal with software licence issues, you should probably try the
scripts/programs in this package first, as most of them don't make permanent
changes to a chip on your motherboard. Changing the NVRAM should be a last
resort. You can retrieve this package from:


Some related links:

   * is
     a Japanese language file with information on reprogramming and
     replacing the NVRAM in a sun4c machine.
   * is a
     Japanese language eeprom-nvram FAQ
   * For other Sun Hardware questions, check out The Sun Hardware Reference
     available from
   * For those who want more technical information about the NVRAM chips
     themselves, SGS-Thomson has a WWW page with datasheets for the M48T02,
     M48T08, and M48T59Y on
   * Useful tools for Sun Workstations at

This document consists of the following parts.

  1. Introduction and Hardware
  2. General sun4c, sun4m, sun4d, sun4u IDPROM Programming
  3. A Quick-and-Dirty Guide to Restoring the NVRAM of a sun4c/m/u Machine
  4. The Sun 3/80
  5. Examples
  6. Odds and Ends
       a. Resetting the NVRAM when Stop-N doesn't work
       b. Attaching a new battery onto an existing M48T02
       c. How to start and stop the NVRAM clock on the Sun 3/80 and sun4c
       d. Other more arcane methods for modifying the IDPROM
       e. The hostid on Solaris 2.5 x86
       f. The NVRAM in sun4 architecture machines
  7. Credits


Introduction and Hardware

Every Sun 3/80, sun4c, sun4u, and sun4m architecture machine contains an
NVRAM chip (not to be confused with the NVRAM in Prestoserve). This NVRAM
chip stores various configuration parameters (e.g. boot device, amount of
RAM to test), maintains the clock, and also contains the IDPROM data, which
is composed of the ethernet address, date of manufacture, hostid, a version
number, and a checksum. The name IDPROM is historical. On older machines
such as the sun2, sun3, and sun4 architecture machines the hostid and
ethernet address were stored in a PROM called the IDPROM.

The sun4d machines (e.g. SS1000) also have an NVRAM chip. However, the
IDPROM information is stored in a flash EEPROM and is downloaded into the
NVRAM during POST. You can also upload the IDPROM information from the NVRAM
chip to the flash EEPROM, so you can change the value of IDPROM in the flash
EEPROM by merely changing the NVRAM and uploading the new values.

This document is for people who want to accomplish one of the following

   * Install a new NVRAM chip in a Sun 3/80, sun4c, or sun4m machine.
     Usually this will be due to NVRAM failure or loss of the NVRAM password
     in full security mode.
   * Change the hostid/ethernet address of a Sun 3/80, sun4c, sun4m, sun4u
     or sun4d machine.
   * Restore a machine with a corrupted NVRAM chip in a Sun 3/80, sun4c,
     sun4u, sun4m machine to working order.

I'm going to focus on methods that involve reprogramming the chip from the
FORTH OpenBoot monitor ("ok" prompt). The OpenBoot monitor uses a modified
version of FORTH, which is a language similar to that used on the HP
calculators which use RPN. You don't need to know any FORTH to reprogram
your IDPROM, but the instructions below might make a little more sense if
you do know some FORTH.

The NVRAM chip will usually have a white or yellow barcode label on it
(except for sun4d). Given the barcode, Sun can reconstruct your original
hostid and ethernet address. On newer machines (some SS5, SS20, all Ultras)
the number printed on the barcode is the last three bytes of the ethernet
address and also the last three bytes of the hostid. The first three bytes
of the ethernet address are always 8:0:20 and the first byte of the hostid
is determined by the system type (see table below), so on these machines you
can trivially reconstruct the hostid. I have no idea how to do it on the
machines with the old style barcode label, but if nothing else, the label
makes the NVRAM chip easy to identify.


The following table gives the location of the NVRAM chip for various models
of Sun workstation.

 3/80                           U0205
 4/60 (SS1)                     U089
 4/40 (IPC)                     U0901
 4/65 (SS1+)                    U089
 4/20 (SLC)                     U1011
 4/25 (ELC)                     U0813
 4/50 (IPX)                     U0512
 4/75 (SS2)                     U0512
 4E                             U1101
 4/10 (SPARCclassic X)          U0707
 4/15 (SPARCclassic)            U0707
 4/30 (LX/ZX)                   U0707
 SPARC Xterm 1                  U1605
 SS4                            U1605
 SS5                            U1506
 SS10                           U1004
 SS20                           U1004
 SS600MP                        U2701
 SS240 (Voyager)                U1506
 SS1000/1000E                   U1007
 SS2000/2000E                   U1205
 U1/170                         U2006

The NVRAM chips are SGS-Thomson Timekeeper (formerly Mostek) chips. They
contain an embedded battery with a fixed life. When the machine is off, the
battery runs down. It is very common for the battery embedded in the
Timekeeper chip in an older Sun (sun4c, sun3x) to fail. The following table
lists the NVRAM chip type by machine architecture:

 sun4c          M48T02
 sun4m          M48T08/18
 sun4d          M48T08
 sun4u          M48T59Y
 sun3x          M48T02

The NVRAM chips used to be designated Mostek MK48T02 etc. These chips come
in various speeds. The newer SGS-Thomson part numbers are M48T02-200PC1 for
the 200ns M48T02, M48T08-100PC1 for the 100ns M48T08. 200ns is adequate for
any Sun, but often the faster chips are easier to come by, and there is no
harm in buying them. If you have trouble tracking down a local SGS-Thomson
distributor, Mouser electronics sells the SGS-Thomson Timekeeper chips
(800-346-6873, 817-483-5712). The Mouser part numbers as of 1995 are slighly
different and are as follows:

 SGS-Thomson   Mouser part number speed  capacity
 M48T02-200PC1 511-M48T02-20PC1   200ns  2kB
 M48T02-150PC1 511-M48T02-15PC1   150ns  2kB
 M48T02-120PC1 511-M48T02-12PC1   120ns  2kB
 M48T08-150PC1 511-M48T08-15PC1   150ns  8kB
 M48T08-100PC1 511-M48T08-10PC1   100ns  8kB
 M48T59Y-70PC1 511-M48T59Y-70PC1  70ns   8kB

As of Oct 1995, the prices for these chips from Mouser range from
US$16.00-23.12. I have no affiliation with Mouser other than as a customer.

Dallas Semicondutor makes a clone of the SGS-Thomson M48T02 chips, the
DS1642. I've had mixed experience using the Dallas chips in a Sun. My
experience is that these chips do not work properly in the following
machines: 3/80, SS2, IPX (they fail POST, but otherwise seem OK). However,
the Dallas chips are reported to work in the following machines: SS1, SS1+,
IPC. I have no idea whether the Dallas chips work properly in the following:
SLC, ELC. You can order the DS1642 chips in 120ns or 150ns speeds (150ns is
fine) directly from Dallas in quantities up to 10 by calling 1-800-336-6933
and giving Dallas a credit card number. Data sheets and distrubutor lists
for Dallas are available from Stanislav Sinyagin
 reports that the M48T12 is another acceptable alternative for
the SS1.

Here are some other sources for M48T02/8/18 chips (if you know of sources
not listed here, please send me email). Any SGS-Thomson distributor that
will sell the chips in small quantities should do. There is a list of
SGS-Thomson distributors at Thanks to, Kenji Oshima , Michael J
C Firth , Bernd Wagner , Werner
Lappessen , Mikael Bergqvist  for
sending me the sources I have here:

   * Farnell Electronic Components (01132 636311) in the U.K.
   * Maplin Electronics (01702 554161) in the U.K.
   * Wakamatsu Tsusho Parts Shop, Mitsuwa Budg. 2F, 1-11-4 Soto-kanda,
     Chiyoda-ku, Tokyo 101 Japan tel. (+81)3-3251-4121 / fax.
   * Jermyn GmbH, Im Dachstueck 6, D-65449 Limburg, phone in Germany : 06431
   * elpro, Am Kreuzer 13, D-64372 Ober-Ramstadt, phone in Germany :
     06154/63570, fax: 06154/635749, email
   * ELFA ( is a Swedish company with branch offices in
     Norway, Denmark, and Finland. Part number for the M48T02 is 73-712-06
     (part name in catalogue: M48T02B-15/ST) and the cost is Skr 182
     (excluding VAT) as of April 1997. Phone numbers:
        o Sweden Order: +46 (0)8 735 35 35, Info 735 35 15
        o Finland Order: 08001 11 827
        o Denmark Order: 8001 20 02
        o Norway Order: 800 10 135


General sun4c, sun4m, sun4d, sun4u IDPROM Programming

If you have a valid NVRAM chip installed (IDPROM is ok) then before doing
anything else, write down a copy of the IDPROM information. You can get it
under Sun OS 4.1.x by running /usr/etc/devinfo -vp or under Solaris 2.x by
executing /usr/sbin/prtconf -vp. Alternatively you can get the IDPROM
information at the OpenBoot monitor "ok" prompt by typing the command
.idprom (yes the "." is part of the command). You'll need this information
if the NVRAM gets screwed up and you need to try and back out.

Step 1.

Go to the OpenBoot monitor (ok prompt). You can do this by turning on your
machine, pressing L1/Stop-A to interrupt the boot sequence, and entering
"new command mode". Alternatively, if your machine is running, just shut
down your operating system.

If you are installing a new NVRAM type set-defaults followed by the 
key and then setenv diag-switch? false followed by the  key.

Generally a machine will reset the NVRAM to the default values (excluding
the IDPROM information) when it detects a new NVRAM. Still, it is good to do
a set-defaults just in case this fails.

Step 2.

The command to reprogram the IDPROM part of NVRAM is "mkp". The format for
the command is


where location is read off the following table (all values are in
hexadecimal). Note that some Sun clones (e.g. Tatung COMPstation 25 with TWS
boot PROM REV 1.7) don't have an "mkp" command. If "mkp" doesn't work on
your system, see the section below entitled Other more arcane methods for
modifying the IDPROM.

 byte(s)     contents
 0           always 01 - format/version number
 1           first byte of hostid (machine type)
 2-7         6 byte ethernet address (first three bytes should be 08,00,20)
 8-b         date of manufacture (usually all 0s, doesn't really matter)
 c           second byte of hostid
 d           third byte of hostid
 e           fourth byte of hostid
 f           IDPROM checksum - bitwise xor of bytes 0-e

As mentioned above, you can look at the complete idprom by executing
.idprom. Bytes c through e in the table above are collectively referred to
as the serial number. If you convert the concatenation of bytes c-e to
decimal, this is the serial number you see when you turn the machine on.

Alternatively, you can use the idprom@ command to get a particular byte from


returns the IDPROM value of byte 


 idprom@ .

prints the IDPROM value of byte  because . is the FORTH command to
print the value on the bottom of the stack.

Now make the changes using mkp. Be very careful and be sure to compute the
checksum after making changes. If you don't, you'll get nasty warnings about
an incorrect IDPROM checksum on boot. A quick and dirty way to compute and
store the checksum in location f is to execute the following at the "ok"
prompt _after_ you have made your changes to locations 0-e.

0 f 0 do i idprom@ xor loop f mkp

Don't change the first byte of the hostid to something that doesn't
correspond to your system type (see table below). Similarly, the first three
bytes of the ethernet address should be (08,00,20). The first byte of the
hostid is often used to determine the architecture when booting from CDROM
on some Sun models. If you don't set the first three bytes of the ethernet
address to 08,00,20 you might get message which says that you have a
defective motherboard (but then I don't know of any other consequences of
changing this to some reasonable value, especially avoid ff:ff:ff:ff:ff:ff
!. On some systems you can get away with changing the first three bytes of
the hostid to more or less anything you want).

If you'd rather not use the table below, you can find out what you should
make the first byte of the hostid by typing real-machine-type . at the "ok"
prompt. Note that real-machine-type may not be defined on some machines with
older boot proms.

e.g. modify the hostid of an IPX to be 57c0ffee and the ethernet address to
be 08:00:20:c0:ff:ee. At the OpenBoot monitor prompt (ok)

1 0 mkp
real-machine-type 1 mkp
8 2 mkp
0 3 mkp
20 4 mkp
c0 5 mkp
ff 6 mkp
ee 7 mkp
0 8 mkp
0 9 mkp
0 a mkp
0 b mkp
c0 c mkp
ff d mkp
ee e mkp
0 f 0 do i idprom@ xor loop f mkp

Step 3.

If you are on an SS1000, type update-system-idprom at the OpenBoot PROM "ok"

For any of the above machines, now type reset at the ok prompt. Your machine
should then attempt to reboot with your new hostid/enet addr.

 The following table matches Sun system models with the first
        byte of the hostid. This is from a posting to
         comp.sys.sun.admin by

 01 2/1x0
 02 2/50
 11 3/160
 12 3/50
 13 3/2x0
 14 3/110
 17 3/60
 18 3/e
 21 4/2x0
 22 4/1x0
 23 4/3x0
 24 4/4x0
 31 386i
 41 3/4x0
 42 3/80
 51 SPARCstation 1 (4/60)
 52 SPARCstation IPC (4/40)
 53 SPARCstation 1+ (4/65)
 54 SPARCstation SLC (4/20)
 55 SPARCstation 2 (4/75)
 56 SPARCstation ELC
 57 SPARCstation IPX (4/50)
 61 4/e
 71 4/6x0
 72 SPARCstation 10 or SPARCstation 20
 80 SPARCstation Classic, LX, 4, 5, SS1000, Voyager, Ultra 1

A Quick-and-Dirty Guide to Restoring the NVRAM of a sun4c/m/u machine

This is for folks who need to replace their NVRAM chip in a sun4c/m/u
machine and don't want to bother with XOR calculations or the details above
with mkp. I am assuming that you have a brand new NVRAM chip in hand. All
numbers below are in hex.

First, decide what ethernet address you want to use and what you want for
the last three byte of the hostid. The ethernet address should begin with
08:00:20. There are no restrictions on the last three bytes of the hostid.
Say the ethernet address is 08:00:20:E3:E4:E5 and the last three bytes of
the hostid are H1, H2, H3. The first byte of the hostid will automatically
be set according to the system type (real-machine-type variable in the
OpenBoot monitor).

Turn off the machine. Remove the old NVRAM chip after noting the
orientation. Insert the new NVRAM chip. Be sure to insert it in the correct
orientation, as installing it in the wrong orientation and powering on the
machine will generally destroy the chip. Power up the machine and bring it
to the "ok" prompt. At the "ok" prompt execute the following

setenv diag-switch? false
8 0 20 E3 E4 E5 H1H2H3 mkpl

mkpl expects some input (but it doesn't prompt you). The input is a
Control-D followed by a Control-R. If mkpl does not print a copyright
notice, then it changed the IDPROM. You should make sure by looking at the
idprom after using mkpl by executing the .idpromcommand

e.g. 8 0 20 13 de ad c0ffee mkpl will set the last three bytes of the hostid
to c0ffee and the ethernet address to 08:00:20:13:de:ad.

N.B. mkpl will only work if the IDPROM checksum is invalid. Otherwise it
will simply print a copyright notice after you type the Control-R. So, if
you can't get mkpl to work, you can try making the IDPROM checksum invalid.
You can invalidate the IDPROM checksum in an NVRAM with a valid IDPROM
checksum by executing f idprom@ 1 xor f mkp. If you still can't get mkpl to
work, then you should try using mkp as described in the above section. This
note was added because on some machines, set-defaults will set the IDPROM
checksum according to the other values in the IDPROM.


The Sun 3/80.

Here's a way to modify NVRAM IDPROM info on a Sun 3/80 (people have to do
this because of the usual battery problem, as with the sun4c machines) This
may not be the most elegant procedure, but this should allow you to modify
the NVRAM IDPROM info on a sun 3/80. At first glance you might think that
the q command would work, but it doesn't seem to actually modify anything
when given addresses >= 0x7d8

Press Stop-A after you turn the 3/80 on

N.B.:^t is a command in the steps below. Don't try control-T. This procedure
has only been tested with 2.9.2 PROMS.

  1. At the > prompt execute the command ^t fef04000. You'll get output
     which includes the following (samples included)

     TIA entry = 33FA500
     TIB entry = 33FB80A

     Write these values down.
  2. Change the TIA entry for fedfa000 to match the above

     > m a fedfa000
     TIA MAP FEDFA000 [...] ? 33FA500

     Type Control-D at the next ? prompt
  3. Change the TIB entry to match the above:

     > m b fedfa000
     TIB MAP FEDFA000 [...] ? 33FB80A

  4. Now change the pagemap entry to match the above

     p fedfa000
     PageMap FEDFA000 [...] ? 64000049

  5. Now enter the new IDPROM values. Use the following table and be sure to
     get the checksum right.

     o fedfa7d8

     Jay York  has provided me with a great simplification
     of the above procedure that I have been unable to test. His procedure
     skips the steps preceeding this last step (o fedfa7d8). Instead, one
     can simply do o fef047d8 and enter the IDPROM values at that point. I
     am leaving the more involved procedure above, because I don't have a
     3/80 to test this simplified procedure.

                                 Sun 3/80 IDPROM

      byte         contents
      fedfa7d8     01
      fedfa7d9     42

      fedfa7da-7df 6 byte ethernet address (first three bytes must be
      fedfa7e0-7e3 date of manufacture (all 0s is fine)
      fedfa7e4     second byte of hostid
      fedfa7e5     third byte of hostid
      fedfa7e6     fourth byte of hostid
      fedfa7e7     checksum - bitwise xor of bytes at fedfa7d8-fedfa7e6
  6. Reset the computer by executing the command k 2. It should come back up
     with the desired hostid and ethernet address.
  7. If you are installing a new M48T02 chip, you'll also need to initialise
     the other values in NVRAM, e.g. boot device, memory, etc. Unlike the
     sun4c machines, the Sun 3/80 does not set these parameters to sane
     defaults when it detects a new M48T02. To modify the rest of NVRAM you
     can use the q command in the monitor. See the table below.

When Sun OS 4.1.x boots, it will kick-start the clock. The first time it
boots it will complain that the TOD is not initialized. It shouldn't
complain the second time the machine boots. However, if you are using Sun OS
4.1 a bug that was fixed in 4.1.1 will prevent the OS from being able to use
the NVRAM clock. One can fix this. change the line in
/usr/include/sun3x/devaddr.h and /usr/kvm/sys/sun3x/devaddr.h from

#define V_CLK1ADDR 0xFEDFC7F8


#define V_CLK1ADDR 0xFEDFA7F8

and then patching the kernel by searching for 0xFEDFC7F8 in the kernel and
changing it to be 0xFEDFA7F8. Thanks to for
this information.

The following table of memory locations in NVRAM for the Sun 3 series
machines is from the Sun Hardware Reference by James W. Birdsall
. I provide it here so you won't have to dig up the
Sun Hardware Reference to restore a 3/80 to working order. I've omitted a
few rows that have nothing to do with the 3/80 (mostly 386i stuff)

  0x14       Installed memory in MB.

  0x15       Tested memory in MB

  0x16       Monitor screen    0x00     1152x900 (standard resolution)
                               0x12     1024 x 1024

                               0x13     1600 x 1280

                               0x14     1440 x 1440

                               0x15     1024 x 768

  0x17       Watchdog reset    0x00     invoke ROM monitor
                               0x12     initate power-on reset (default)

  0x18       Boot device       0x00     poll (default)

                               0x12     boot from EEPROM/NVRAM specified
                                        boot device

  0x19-0x1a  SunOS boot        0x78     xy
             device name (in   0x79
                               0x78     xd

                               0x73     sd

                               0x69     ie

                               0x69     id

                               0x6c     le

  0x1b-0x1d  SunOS boot        0x00     (0,0,0) (default)
             device            0x00
             controller,       0x00
             unit, partition

  0x1f       Primary terminal  0x00     monochrome FB

                               0x10     serial port A

                               0x11     serial port B

                               0x12     0x12 VMEbus and 3/60-P4 color
                                        frame buffers (configure locations
                                        0x60c-0x613 when VX and MVX
                                        graphics options are installed)

                               0x20     non-3/60 P4 color frame buffer

  0x20       Power-up banner   0x00     Sun logo display

                               0x12     custom banner stored in 0x68-0xb7

  0x21       Keyboard click    0x00     off

                               0x12     on

  0x22-23    Diagnostic boot   Used when NORM/DIAG switch is in DIAG
             device name (in   position. On the 3/80 there isn't a switch,
             ASCII)            NORM/DIAG mode is controlled by location
                               0x70b. As in 0x1b-0x1d or 0x00, 0x00 to
                               invoke the PROM monitor

  0x24-0x26  Diagnostic boot device controller, unit, partition number

  0x28-0x4f  Diagnostic boot   Used when in DIAG mode. ASCII codes for
             path              path and filename to boot, or all zeros to
                               invoke ROM monitor

  0x50       High resolution number of columns

  0x51       High resolution number of rows

  0x58       Serial port A     0x00     9600
             default baud
             rate              0x12     use rate stored at 0x59-0x5a

  0x59-0x5a  Serial port A     The baud rate as a 16-bit number, MSB first
             baud rate         (e.g. 0x04 0xb0 for 1200)

  0x5b       Serial port A     0x00     assert DTR and RTS
                               0x12     do not assert DTR and RTS

  0x60       Serial port B     0x00     9600
             default baud
             rate              0x12     use rate stored at 0x61-0x62. Note
                                        that when in DIAG mode, port B
                                        runs at 1200 baud and the settings
                                        in 0x60-0x62 are ignored

  0x61-0x62  Serial port B     The baud rate as a 16-bit number, MSB first
             baud rate         (e.g. 0x04 b0 for 1200)

  0x63       Serial port B     0x00     assert DTR and RTS
                               0x12     do not assert DTR and RTS

  0x68-0xb7  Custom banner     ASCII codes for desired banner, padded with
                               spaces and ending with 0x0D, 0x0A in
                               locations 0xB6 and 0xB7

  0x18f      Logo type         0x00     normal Sun logo

                               0x06     3D logo for CG6

                               0x12     custom logo

  0x492      Password mode     0x01     command secure mode
                               0x5e     fully secure mode

                               other    non-secure mode

  0x493-a    Password          Eight bytes of password in ASCII. If the
                               ROM is 2.8, enter a '@' character before
                               each letter of the password. Enter one
                               letter per location, followed by Return. If
                               the password is less than eight letters,
                               enter 0x00 in the remaining locations. The
                               hexadecimal values of the letters can also
                               be used to enter the password.

  0x70b      3/80 power-on     0x06     normal boot
                               0x12     diagnostic boot

                               other    diagnostic boot



N.B. As I said above, you should be careful that the first byte of the
hostid matches the system type.

  1. Modify the hostid of an IPX to be 57c0ffee and the ethernet address to
     be 08:00:20:c0:ff:ee. At the OpenBoot PROM monitor prompt

     01 0 mkp
     57 1 mkp
     08 2 mkp
     0 3 mkp
     20 4 mkp
     c0 5 mkp
     ff 6 mkp
     ee 7 mkp
     57 8 mkp
     0 9 mkp
     0 a mkp
     0 b mkp
     c0 c mkp
     ff d mkp
     ee e mkp
     29 f mkp

     Notice the simplification in the above example. If you make the
     ethernet address 08:00:20:H1:H2:H3 and the four bytes of the hostid
     ST,H1,H2,H3 where ST is the system type byte, and you put ST,0,0,0 in
     the date of manufacture field, then the IDPROM checksum will always be
     29 (remember all of these numbers are hexadecimal). This make things a
     bit easier, you can, in general, just enter

     01 0 mkp
     real-machine-type 1 mkp
     08 2 mkp
     0 3 mkp
     20 4 mkp
     H1 5 mkp
     H2 6 mkp
     H3 7 mkp
     real-machine-type 8 mkp
     0 9 mkp
     0 a mkp
     0 b mkp
     H1 c mkp
     H2 d mkp
     H3 e mkp
     29 f mkp

     and you don't need to calculate the checksum since it will always be
  2. Change the hostid of an SS10 to be 72c0ffee and the ethernet address to
     be 08:00:20:c0:ff:ee.

     01 0 mkp
     72 1 mkp
     08 2 mkp
     0  3 mkp
     20 4 mkp
     c0 5 mkp
     ff 6 mkp
     ee 7 mkp
     0 8 mkp
     0 9 mkp
     0 a mkp
     0 b mkp
     c0 c mkp
     ff d mkp
     ee e mkp
     0 f 0 do i idprom@ xor loop f mkp

  3. Change the hostid of an SS1000 to 80c0ffee. Leave the ethernet address
     and the date of manufacture intact. Note that the system type byte for
     the SS1000 is 0x80

     c0 c mkp
     ff d mkp
     ee e mkp
     0 f 0 do i idprom@ xor loop f mkp

  4. Install a new NVRAM in an IPX. Set the hostid to 57c0ffee and the
     ethernet address to be 08:00:20:c0:ff:ee .
       1. Turn the machine off.
       2. Remove the old NVRAM chip
       3. Install the new NVRAM chip. Be sure to get the orientation right.
       4. Turn the machine on.
       5. At the OpenBoot monitor prompt execute the following commands:

          setenv diag-switch? false
          8 0 20 c0 ff ee c0ffee mkpl

          where ^D represents Control-D, etc.


Odds and Ends.

Resetting the NVRAM (when Stop-N doesn't do it)

You might want to do this to recover from the loss of an NVRAM password (in
full security mode) or if you mess up your nvramrc. I think that the safest
thing to do is pay the $20 for a new Timekeeper chip. But several people
have reported to me success hot-swapping the NVRAM (i.e. removing and
installing a new chip when the system is on). (Stephen Dowdy) writes:
> (this may apply to other SPARC models.)
> IPC --  remove NVRAM, power-up without.  *carefully* hot-plug it in when OK
>     prompt comes up (after it says CHECKSUM failure).  do:
>         OK set-defaults
>         OK set-defaults
>     then power-cycle
> SS2 --  you need to boot from a good NVRAM, then hot-swap the "bad" one
>     and "set-defaults".  Only if the L1-N (or is it L1-D) thingy
>     doesn't work for you.

Attaching a new battery onto an existing M48T02

My take on this procedure is that it isn't worth trying to save the US$20 it
would take to buy a new M48T02. This procedure requires considerable care.
I'm including this excerpt from the old NVRAM FAQ for completeness.

The contents of the (nv)ram are backed up by a 3V lithium battery. It's
located together with a quartz on top of the ram in a kind of backpack. The
battery is on the side that's opposed to the dot marking pin 1, next to pin

                       / _battery
                      / /
                   | O O | <-- cut here
             Pin 1

At the point marked above, some kind of nose is reaching down from the
backpack over the resin. Carefully cut through the polyester resin filling
the dimple. This works best with some kind of mini drill with a small
milling head or a razor knife. Buried in the resin you'll find two small
diagonal metal connectors :).

Be careful not to short-circuit them, or you'll loose the contents of your
nvram (if it was still able to keep them). -That's why you should save them
*before* :)

The connector closest to pin 12 is ground, the other (opposing) one +3V. You
can now solder some wire to them and connect them to a new 3V lithium

How to start and stop the NVRAM clock on the Sun 3/80 and sun4c machines

The following information on starting and stopping the clock in the NVRAM
chip on the Sun 3/80 was contributed by I've
added the tables and the sun4c information below. As it says below, you
don't normally need to do this. Sun OS will take care of starting the clock
on a new NVRAM chip for you.

Procedure to 'kick start' a new MK48T02 NVRAM clock chip on Sun 3/80

WARNING : This procedure is intended to be used on new, blank NVRAM chips only.
If you are using it on an existing NVRAM (for some unknown reason) you should
follow the procedures described in 'Backing up your NVRAM'.

This procedure shouldn't normally be necessary as SunOS provides this
functionality as part of the normal clock initialisation.  However, it may
prove useful in unforeseen circumstances.

The step numbers correspond to the step numbers in the SGS-Thomson
data sheet procedure for 'kick starting' the clock.

The data sheet warns NOT to leave the kick start bit set to 1 for normal use
as this will cause excessive current drain and shorten the life of the battery.
It does not mention if this is dangerous or by how much the life of the battery
is shortened...:-(

The kick start bit is the MSB in location 7FB

(The old NVRAM contents will be displayed by the monitor in the place
marked XX in the steps below.)

First halt the machine and get to the monitor prompt.

> q 7f8
EEPROM 7F8: XX? 80              Step 1. Set write bit (enable write)
EEPROM 7F9: XX? 0               Step 2. Reset stop bit (not stopped)
EEPROM 7FA: XX? (Press Enter)
EEPROM 7FB: XX? 80              Step 3. Set kick start
> q 7f8
EEPROM 7F8: XX? 0               Step 4. Reset write (disable write)
                                Step 5. Wait for 2 seconds.
> q 7f8
EEPROM 7F8: XX? 80              Step 6. Set write bit
EEPROM 7FA: XX? (Press Enter)
EEPROM 7FB: XX? 0               Step 7. Reset kick start
> q 7f9
EEPROM 7F9: XX? 0               Step 8. Set a dummy time & date...
> q 7f8
EEPROM 7F8: XX? 0               Step 9. Reset write bit

And that's it.
Double check that the Kick Start bit is set to zero by doing the following :

> q 7fb

XX should be a value less than 80 Hex.  If it isn't repeat the procedure

The related and opposite function to this is Stopping the Clock in the NVRAM.
When the clock is stopped, the storage life of the battery is extended because
the oscillator is not running.  This might be useful if you intend to put the
machine into storage or not use it for a while.

Again, halt the machine and get to the monitor prompt.

> q 7f8
EEPROM 7F8: XX? 80              Set write bit
EEPROM 7F9: XX? 80              Set stop bit
> q 7f8
EEPROM 7F8: XX? 0               Reset write bit

Simon Allen 1996.

As Simon Allen mentions, the kick-start procedure is not normally necessary
as Sun OS automatically starts the lock in an NVRAM with a stopped clock.
However, if you are putting a machine into long term storage, it is nice to
be able to stop the clock as doing this will significantly lower current
drain on the battery. The following information from the M48T02 data sheet
gives information on the clock.

                      The M48T02 Register Map

 Address                                                 Function
        Bit 7 Bit 6 Bit 5 Bit 4Bit 3 Bit 2 Bit 1 Bit 0
   7ff  -     -     -     -    -     -     -     -       Year 00-99
   7fe  0     0     0     -    -     -     -     -      Month 01-12
   7fd  0     0     -     -    -     -     -     -       Date 01-31
   7fc  0     FT    0     0    0     -     -     -        Day 01-07
   7fb  KS    0     -     -    -     -     -     -      Hours 00-23
   7fa  0     -     -     -    -     -     -     -    Minutes 00-59
   7f9  ST    -     -     -    -     -     -     -    Seconds 00-59
   7f8  W     R     S     -    -     -     -     -    Control

   * ST is STOP BIT
   * W is WRITE BIT
   * R is READ BIT
   * S is SIGN BIT

Instructions for starting the clock

  1. Set the Write Bit to 1
  2. Reset the Stop Bit to 0
  3. Set the Kick Start Bit to 1
  4. Reset the Write Bit to 0
  5. Wait two seconds
  6. Set the Write Bit to 1
  7. Reset the Kick Start Bit to 0
  8. Set the Correct Time and Date
  9. Reset the Write Bit to 0

N.B. Leaving the KS bit set will cause the Clock to draw excessive current
and will shorten the battery life.

Instructions for stopping the clock

  1. Set the Write Bit to 1
  2. Set the Stop Bit to 1
  3. Reset the Write Bit to 0

Given the above tables, Simon Allen's instructions for the 3/80, and the
next section on which tells how to map the NVRAM to virtual memory on sun4c
machines, it is a relatively easy matter to see how to stop and start the
clock on a sun4c machine.

Stopping the clock on a sun4c machine

2000000 obio 0 map-page             map NVRAM to page 0
80 7f8 c!                           set write bit
80 7f9 c!                           set stop bit
0 7f8 c!                            reset write bit

Starting the clock on a sun4c machine

2000000 obio 0 map-page             map NVRAM to page 0
80 7f8 c!                           set write bit
0 7f9 c!                            reset stop bit
80 7fb c!                           set kick start
0 7f8 c!                            reset write bit
wait for two seconds

80 7f8 c!                           set write bit
0 7fb c!                            reset kick start

0 7f9 c!                            set dummy time and date
0 7fa c!                            (if necessary)
0 7fb c!
4 7fc c!
11 7fd c!
1 7fe c!
96 7ff c!

0 7f8 c!                            reset write bit

Other more arcane methods for modifying the IDPROM

mkp and mkpl are not the only way to modify the IDPROM. Before I discovered
these commands, I used to use procedures like the ones below. The material
in this section assumes that you have access to the OpenBoot PROM manual
which is part of the Solaris 2.x Answerbook.

You can use the OpenBoot monitor to find the virtual address of the NVRAM.
The basic steps are:

  1. cd to the eeprom device (you can find its exact name via show-devs)
  2. execute .attributes or .properties depending upon whether you have V2
     or V3 of the OpenBoot PROM.
  3. execute device-end followed by reset

For example

    ok show-devs
    ok cd /obio/eeprom@0,200000
    ok .attributes
    address: ffee9000
    ok device-end
    ok reset

From this point, you can modify and look at the NVRAM by using the c!,
dump,and c? commands in the OpenBoot PROM. You can also get the virtual
address of the NVRAM by looking at the output of /usr/etc/devinfo -vp under
Sun OS 4.1.x or /usr/sbin/prtconf -vp under Solaris 2.x. On sun4c machines,
the IDPROM starts at offset 0x7d8 from the start of the NVRAM. On sun4m,
sun4d, and sun4u machines the offset is 0x1fd8.

From here one can also find the physical address of the NVRAM using pgmap?.
In the above example, if we type ffee9000 pgmap? at the OpenBoot prompt, we
get a few lines of output, one of which is

Physical: 0.7120.0000

which means on this machine the physical address is 71200000 in address
space 0.

You can also use map-page to map the physical address of the page containing
the IDPROM to virtual address 0. To do this you need to know the physical
address of the NVRAM. You can find it as above or just use the following

 machine type                        address   space arch -k

 SS1, SS1+, SS2, ELC, IPC, IPX, SLC  02000000  obio  sun4c

 Classic, LX, SS5, SS4, Voyager      71200000  0     sun4m

 SS10, SS20, 6x0/MP                  f1200000  f     sun4m

 SS1000                              00280000  f     sun4d

For the sun4m and sun4d machines, the page size is 4kB (0x1000) so the
simplest thing to do is map the second page of the NVRAM. This is because
we're using map-page and it only maps one page at a time.

e.g. Modify the hostid of an IPX to be 57c0ffee and the ethernet address to
be 8:0:20:c0:ff:ee

02000000 obio 0 map-page
1 7d8 c!
57 7d9 c!
08 7da c!
0 7db c!
20 7dc c!
c0 7dd c!
ff 7de c!
ee 7df c!
57 7e0 c!
0 7e1 c!
0 7e2 c!
0 7e3 c!
c0 7e4 c!
ff 7e5 c!
ee 7e6 c!
29 7e7 c!

e.g. to modify the hostid of an SS10 to be 72c0ffee and the ethernet address
to be 08:00:20:c0:ff:ee, do the following

f1201000 f 0 map-page
01 fd8 c!
72 fd9 c!
08 fda c!
0 fdb c!
20 fdc c!
c0 fdd c!
ff fde c!
ee fdf c!
72 fe0 c!
0 fe1 c!
0 fe2 c!
0 fe3 c!
c0 fe4 c!
ff fe5 c!
ee fe6 c!
29 fe7 c!

Note that we added 0x1000 to the physical address in the above table, as
explained above.

The hostid on Solaris 2.5 x86

Intel processor machines don't have an IDPROM. Sun uses a different
mechanism to generate the hostid. When the operating system is initially
installed a pseudo-random hostid is generated. It appears that this
pseudo-randomly generated hostid will always be between 1 and 3b9aca00. The
hostid is based on eight bytes of serialisation information in the kernel
module /kernel/misc/sysinit. This is in contrast to the situation on SPARC
machines where the hostid is based on the IDPROM.

/kernel/misc/sysinit contains code which initialises the variable hw_serial
in the kernel based on the serialisation information. On both SPARC and x86
versions of Solaris 2.5, hw_serial stores the hostid as a decimal C string.

Other than the eight bytes of serialisation information the
/kernel/misc/sysinit files do not differ between machines. Four of the
serialisation bytes depend upon the other four bytes, so the hostid is
somewhat tamper resistant. If the serialisation information is tampered with
carelessly or the sysinit module fails to load for some other reason, the
hostid of the machine will be 0. A little more obfuscation is done in the
code, i.e. hw_serial is not referenced directly in the module, but
indirectly via the pointer _hs1107.

This means that if you need to have two machines with the same hostid for
some reason (say, to have a backup server with the same hostid in case your
primary server malfunctions), you can just copy the /kernel/misc/sysinit
file from one machine to another.

Moreover, it seems that initialising hw_serial is the only function
performed by the sysinit module. Hence, it is a simple matter to replace
/kernel/misc/sysinit yielding a machine with whatever hostid one wants, by
compiling a simple C program for a loadable kernel module which sets
hw_serial to the desired value.

C code for a generic replacement sysinit module is included in change sun
hostid which is available from the sites listed near the beginning of this
document. Replacing part of the operating system is probably not the best
way to achieve this effect. In general, I'd recommend using one of the other
modules in change sun hostid as there is less risk of damaging things and
rendering the system unbootable, but a few people have asked for this.

The NVRAM in sun4 architecture machines

The sun4 machines (e.g. Sun 4/1xx, 4/2xx, 4/3xx, etc.) also have M48T02
chips. These chips do not store the hostid and ethernet address, which are
in an actual PROM, but they do keep track of the time of day and the system
configuration information. Replacing the NVRAM chip is a relatively simple
matter, the only trick is to set the appropriate values in the Sun PROM
monitor using the q command then boot the operating system to kick-start the
clock. You can use the table for the Sun 3/80 to set the values in the old
Sun PROM monitor. The only significant difference is that normal/diagnostic
boot is controlled by a physical switch instead of the byte at location
0x70b. See the Sun Hardware Reference (referred to above), your machine
documentation, or the Sun FE Handbook if you need more information on the
Sun PROM monitor.



I'd like to thank the following people who have helped make this a better
document. If I've left anyone off this list who should be on it please drop
me a note and I'll add the name to the list.

   * Kevin Murty for the use of an SS1000 for testing
   * for the kick-start information,
     information on the Sun OS 4.1 clock bug on the 3/80, a U.K. source of
     NVRAM chips.
   * Michael Firth  for a U.K. source of NVRAM
   * (Stephen Dowdy)
   * (Denis Solaro)
   * (Michael Coughlin) for numerous suggestions
     and bits of information.
   * Kenji Oshima  for the GIF image of a M48T02 and a
     source for replacement NVRAM chips in Japan.
   * Eddie Berin
   * Marek Jedryszek 
   * Andy Michael 
   * Bernd Wagner 
   * Lonnie Borntreger <>
   * Jay York 
   * James Lin 
   * Werner Lappessen 
   * Stanislav Sinyagin 
   * Mikael Bergqvist